(a) No telecommunications carrier shall offer or provide noncompetitive telecommunications service, telecommunications service subject to subsection (g) of Section 13-506.2 or Section 13-900.1 or 13-900.2 of this Act, or telecommunications service referred to in an interconnection agreement as a tariffed service unless and until a tariff is filed with the Commission which describes the nature of the service, applicable rates and other charges, terms and conditions of service, and the exchange, exchanges or other geographical area or areas in which the service shall be offered or provided. The Commission may prescribe the form of such tariff and any additional data or information which shall be included therein.
     (b) After a hearing regarding a telecommunications service subject to subsection (a) of this Section, the Commission has the discretion to impose an interim or permanent tariff on a telecommunications carrier as part of the order in the case. When a tariff is imposed as part of the order in a case, the tariff shall remain in full force and effect until a compliance tariff, or superseding tariff, is filed by the telecommunications carrier and, after notice to the parties in the case and after a compliance hearing is held, is found by the Commission to be in compliance with the Commission’s order.
     (c) A telecommunications carrier shall offer or provide telecommunications service that is not subject to subsection (a) of this Section pursuant to either a tariff filed with the Commission or a written service offering that shall be available on the telecommunications carrier’s website as required by Section 13-503 of this Act and that describes the nature of the service, applicable rates and other charges, terms and conditions of service. Revenue from competitive retail telecommunications service received by a telecommunications carrier pursuant to either a tariff or a written service offering shall be gross revenue for purposes of Section 2-202 of this Act.